June 20, 1954
NOTES
loids. This was chromatographed on 150 g. of neutral alumina (activity II-III)13 and from the 7:3 benzene-ether eluates was isolated 2.0 g. of pilocereine. Crystallization from ethyl acetate furnished 1.1 g. of pure pilocereine, the identity of which was confirmed by mixture melting point and infrared Comparison. L. gatesii.'"Fresh cactus (3.3 kg.) yielded 300 g. of dry Dowdered material which on extraction gave 39.6 P. of residue. This was partitioned and separated as previously described into 3 g. of phenolic and 5.4 g. of non-phenolic base. The non-phenolic base was chromatographed on 150 g. of alumina to yield 1.5 g. of pilocereine identified as before. Isolation of Anhalonidine from Lemaireocereus meberi.14By the usual procedure 9.27 kg. of cactus gave 48 g. of alcoholic residue which was extracted with ether until no more color was removed. The ether extract, weighing less than 2 g., did not contain alkaloids (Mayer's reagent) and only traces of oily material were obtained when this fraction was processed in the usual manner for triterpenes. The dark brown, ether-insoluble fraction (46 g.) was refluxed for 3 hr. with 1 1. of methanol and 200 cc. of concentrated hydrochloric acid. After cooling and dilution with water this was extracted with ether but evaporation left only traces of oily material. The aqueous acidic solution was neutralized with ammonium hydroxide and extracted with ether; evaporation yielded 1.73 g. of crude alkaloids which were chromatographed on 100 g. of activated alumina. Elution with chloroform-methanol (99: 1) furnished a solid (0.65 9.) crystallizing as needles, m.p. 156-158" from acetonehexane. The analytical sample after recrystallization from acetone showed m.p. 161-161.5'; reported's for anhalonidine, m.p. 160-161'. Anal. Calcd. for C W H I ~ N O X C.: 64.55: H. 7.68: N. 6.27; ( O C H Z ) ~ 27.6; , nek:'equiv., 223. Found: C, 64.43; H, 7.80; N, 6.50; OCHa, 26.9; neut. equiv., 215. The picrate, prepared by adding a saturated solution of picric acid t o a solution of the base gave needles, m.p. 200.5201.5', after recrystallization from ethanol; reported's m.p. 201-208'. Anal. Calcd. for ClsHzoNaOlo: C, 47.79; H, 4.46. Found: C, 48.03; H , 4.54.
troxyalkyl)-3-nitroguanidines,the free bases af
3217
which are isomeric to those reported by McKay and Wright.4 The cyclization of 1-(w-nitroxypropy1)- and l-(@-nitroxy-t-butyl)-3-nitroguanidine proceeded rapidly in boiling n-butanol to l-nitroamino-A2-1,3-diazacyclohexene nitrate and 1-nitro2-amino-4-dimethyl-A2-lI3-diazacyclopentene nitrate, respectively. However, l -(w-nitroxybutyl) and l-(w-nitroxyamyl)-3-nitroguanidine failed to cyclize to the respective seven- and eight-membered rings: viz., 1-nitro-2-amino-A2-1,3-diazacycloheptene and 1-nitro-2-amino-A2-l,3-diazacyclooctene nitrate salts. Failure of the higher homologs to cyclize can be attributed to the greater strain in the seven- and eight-membered rings. I n addition, attempts to prepare 1-nitro-2-amino-4-ethyl-A2-1,3diazocyclopentene nitrate by cyclizing l-(a-nitroxy-@-butyl)-3-nitroguanidine were unsuccessful. Experimental5
1-(o-Hydroxypropyl)-3-guanidinium Nitrate.-Seventyfive grams (1.0 mole) of 3-amino-1-propanol (obtained from American Cyanamid; b.p. 85' (10 mm.)) was added, slowly with stirring, to 139.2 g. (0.5 mole) of 2-methyl-2-thiopseudouronium sulfate in a 1-liter beaker. Thirty cc. of water was then added to the mixture. Considerable foaming and evolution of methyl mercaptan occurred immediately. The reaction mixture was allowed to stand overnight a t room temperature. The product, a clear, viscous oil, was treated with an equivalent weight of hot aqueous barium nitrate solution. The barium sulfate precipitate was removed by filtration, and the filtrate evaporated yielding 108 g. (60.0% yield) of crude product which melted a t 85-88'. One crystallization from 95% ethanol raised the m.p. to 91--92". Anal. Calcd. for C4H1&404: C, 26.6; H, 6.7; N, 31.1. Found: C,26.7; H, 6.9; N, 31.0. (15) E. Spaeth, Monafsh., 43, 477 (1922). The picrate salt, crystallized from ethanol, melted a t 127-128'. DEPARTMENT OF CHEMISTRY Anal. Calcd. for ClOH14NBO8: C, 34.9; H , 4.1; N, WAYNEUNIVERSITY 24.4. Found: C,34.8; H , 4.3; N, 24.3. AND DETROIT,MICHIGAN, INSTITUTO DE QUIMICA 1-( W-Hydroxypropyl)-3-nitroguanidine.-1-( o-HydroxyUNIVERSIDAD NACIONAL AUTONOMA DE hfEXIC0 propyl)&nitroguanidine was prepared in 90% yield by the CIUDADUNIVERSITARIA procedure of Fishbein and Gallaghad utilizing 2-methylMEXICO,D. F. 1(or 3)nitro-2-thiopseudourea and 3-amino-l-propanol . The crude m.p. of 123-126' was raised to 128-129" by one crystallization from 95% ethanol. Some New l-(Nitroxyalkyl)-3-nitroguanidines and Anal. Calcd. for C4HlaN40J: C, 29.6; H , 6.2; N, 34.6. Found: C,29.4; H,6.1; N,34.3. their Cyclic Products' 1-(~0-Nitroxypropyl)-3-nitroguanidine. 1. From 1BY LAWRENCE FISHBEINAND JOHN A. GALLAGHAN (~-Hydroxypropyl)-3-ganidinium Nitrate .-Forty-three grams (0.23 mole) of I-( w-hydroxypropyl)-3-guanidinium JANUARY 18, 1954 RECEIVED nitrate was added portionwise to a nitrating mixture comThe cyclization of the N-(@-substituted ethyl)- posed of 88.0 g. of 95% sulfuric acid and 30 g. of 98% nitric and N-(@-nitroxypropy1)-N'4troguanidines to acid. The nitration was performed a t 0-5'. After stirfor five minutes the mass was poured into 500 g. of ice; salts of 1-nitro-2-amino-A2-1,3-diazacyclopentenering the contents were stirred for an additional five minutes and and 1-nitro-2-amino-5-methyl-A2-1,3-diazacyclofiltered. Forty-four grams (93.1% yield) of white crystals pentene nitrate, respectively, was first reported by was obtained, which on crystallization from 95% ethanol McKay.2 A six-membered ring compound has also (350 cc.) gave 33 g. of crystals melting a t 121-122'. Anal. Calcd. for C ~ H ~ N ~ OC,S 23.2; : H , 4.3; K, 33.8. been formed by cyclizing N-( y-nitroxybuty1)-N 'Found: C, 23.0; H , 4.5; N, 33.8. nitroguanidine to 1-nitro-2-amino-6-methyl-A2-l,32. From I-(o-Hydroxypropyl)-3-nitroguanidme.-1-(odiazacyclohexene nitrate. Hydroxypropyl)-3-nitroguanidine was nitrated according It was of interest to this Laboratory to determine t o the procedure of McKay and Milks.% An 85y0 yield of whether larger ring systems could be synthesized product was obtained melting a t 121-122'. A mixed m.p. through cyclization of higher homologs of 1-(ni- with an authentic sample was not depressed. l-Nitro-2-amino-Aa-l ,3-diazacyclohexene Nitrate .-Ten (1) Publication approved b y the Bureau of Ordnance, N a v y Departgrams (0.05 mole) of l-(o-nitroxypropyl)-3-nitroguanidine ment. was dissolved in 25 cc. of boiling n-but:mol. After five (2) (a) A. F. McKay arid J . E. Milks, THISJOURNAL, 72, I G l f i minutes of refluxing, 3 cryst:illitie precipitate forinad. The (1950); (b) A. F McKay, Chem. Rcss., 61, 340 (1952): (c) R. 11. Hall, A. F . McKay and G . F Wright, THISJOURNAL, 73, 2205 (1951); (d) A. F. McKay. J . Org. Chem., 16, 1395 (1951); (e) A. F. McKay and R . 0. Brawn, ibid., 16, 1829 (1951). (3) A. F. McKay and H. P. Thomas, Can. J . C h c m . , 2 9 , 3 9 1 (1951).
(4) A. F. RIcKay and G F Wright, T H I SJ O U R N A70, L 430 (1948) ( 5 ) All melting points are uncorrected. (6) L. Fishbein and J. A Gallaghan, THIS J O U R X A L7,6 , 1877 (1954).
3218
NOTES
Vol. 76
crystals, removed by filtratioii, mere crystallized from 95% Ana2. Calcd. for CsH14N404: C, 30.9; H, 7.2; N, 28.3. ethanol yielding 7 g. of cyclic product melting at 172-173'. Found: C, 30.5; H, 7.0; N, 28.5. Anal. Calcd. for CqHgNjOj: C, 23.1; H, 4.4; N, 33.8. The picrate salt, crystallized from ethanol, melted at 153Found: C,23.0; H , 4 . 5 ; N, 33.8. l55O. l-Nitro-2-amino-A~-l,3-diazacyclohexene nitrate (0.35 g., Anal. Calcd. for CllH16N608: c, 36.6; H, 4.5; N, 23.3. 0.001 mole) was dissolved in 5 cc. of water and treated with Found: C, 36.4; H , 4.3; N,22.8. a saturated picric acid solution. A crystalline picrate l-(.w-Nitroxybutyl)-j-nitroguanidine.-I-( w-Nitroxybu( m .p. 205-207') separated immediately. One crystallizaty1)-3-nitroguanidine was prepared in 70% yield by a n tion from 95% ethanol raised the m.p. t o 207-208" dec. analogous procedure for the preparation of 1-(w-nitroxyA n a l . Calcd. for C~OHIIXIOS: C, 32.2; H, 3.0; N, 26.3. propyl)-3-nitroguanidine. The m.p. 103.5-105.5' was Found: C,32.4; H , 3 . 1 ; N,25.9. raised to 105-106" by two crystallizations from ethanol. 1-Nitro-2-amino-A2-1 ,J-diazacyclohexene .-Two cc. of Anal. Calcd. for CjHl1NsOj: C, 27.1; H, 5.0; N, 31.7. concentrated ammonium hydroxide was added to a solution Found: C, 27.1; H , 5.0; N, 3 1 5 . of 0.5 g. (0.003 mole) of l-nitro-2-amino-A*-l,3-diazacyclol-(w-Nitroxybutyl)-3-nitroguanidine(1.0 g., 0.001 mole) hesene nitrate in 4 cc. of water. A white crystalline product separated immediately. This product was removed by was refluxed with 8 cc. of n-butanol for one hour. After removal of the solvent, 0.9 g. of the original compound was filtration and washed with 5 cc. of cold water. A yield of 0.25 g. (6801,) was obtained. The m.p. of 81-82' was recovered unchanged. No cyclic product could be obtained when the reflux period was extended to four hours. A mixed raised t o 83-84" after one crystallization from ethanol. m.p. of the recovered substance with a n authentic sample Anal. Calcd. for CaH8S40?:C, 33.3; H , 5 . 5 ; N , 38.8. was not depressed. Found: C, 32.9; H, 5.3; X, 38.4. I-( w-Nitroxybuty1)-1,3-dinitroguanidinewas prepared in 1,j-Dinitraminopropane from 1-(w-Nitroxypropyl)-3-ni- 34.8% yield according to the procedure of McKay and troguanidine.-Two grams (0.01 mole) of 1-(w-nitroxy- Milks." The compound, crystallized from ethanol, melted propyl)-3-nitroguanidinemas added portionwise a t 10" to a at 92-93'. nitrating mix consisting of 3 cc. of 95% sulfuric acid and 1.5 Anal. Calcd. for C~HIOSGO;: C, 22.5; H , 3.7; S , 31.6. cc. of 98% nitric acid. The contents were kept at 0" over- Found: C , 2 2 . 3 ; H , 3.6; N,31.5. night, allowed t o warm slowly to 10",and then added to 10 l-(w-Xitroxybutyl)-l-nitroso-3-nitroguanidine was preg. of ice. The product, 1.0 g. (77% yield) melted a t 6466'. One crystallization from ethanol raised the m.p. to pared in 50% yield according t o the procedure of McKay and The yellow crystalline product, crystallized from 66-67'.? It was identified by a mixed melting point of an authentic sample obtained by the hydrolysis of 1,3-dinitro- ethanol, melted at 99-101". Anal. Calcd. for CaHloNsOs: C, 24.0; H, 4.0; N, 33.0. 1,3-diazacyclohexanone-2. 1,3-Dinitro-1,3-diazacyclohexanone-2from l-Nitro-2- Found: C, 23.9; H , 3 . 9 ; N, 33.2. amino-A2-l ,3-diazacyclohexene Nitrate .-1-IGtro-2-aminol-(oi-Hydroxy-p-butyl)-j-guanidiniumSulfate .--'-AminoA2-1,3-diazacyclohexene nitrate mas converted to 1,3-di- I-butanol (Commercial Solvents; 17.5 g., 0.2 mole) was nitro-l,3-diazacyclohexanonc-2 in 75'70 yield by the procc- added to 27.8 g. (0.1 mole) of 2-methyl-2-thiopseudourodure of McKay and Wright.8 Thc product melted a t 121nium sulfate in 20 cc. of water. The reaction was extremely 122". It was identified by a mixed m.p. determination and sluggish in contrast to the preparation of 1-(w-hydroxyhydrolysis t o 1,3-dinitraminopropanc ( m .p. 66-67'). butyl)-3-guanidinium sulfate. The contents was allowed t o 1-( w-Nitroxypropyl)-l-nitroso-3-nitroganidine .--1-( w-Ni- stand a t room temperature for one week, after which the tros?.prop?-l)-3-nitroguanidiiie was nitrosated according t o clcar solution was evaporated almost t o dryness. The addithe procedure of hlcKay and Milks.?& .4 607, yield of prod- tion of 200 cc. of absolute ethanol caused the crystalline 1uct was obtained, melting a t 113-116'. One crystallization (n-hydroxy-p-butyl)-3-guanidinium sulfate (m .p. 173-176', from 95Y0 ethanol gave a crystalline product melting a t 11640% yield) to separate. One crystallization from a 1 : 1 118 ether-ethanol mixture raised the m.p. to 175-177'. The A n a l . Calcd. for C4HsSeOs: C, 20.3; H , 3.1; N , 33.6. compound contained one molecule of water of crystallization. Found: C , 20.2; H , 3.6; N, 35.0 A n a l . Calcd. for C I O H ~ O O ~ NC, ~ S31.7; : H , 7.9; N, 1-(w-Nitroxypropy1)- 1,3-dinitroguanidine .--1-( w-Nitroxypropyl)-l,3-dinitt-oguaiiidinewas prepared in 31.7% yield 22.2. Found: C, 31.3; H, 7.9; N, 22.1. from 1-(w-nitroxypropyl)-3-nitroguanidineby thc procedure The picrate salt, crystallized from ethanol, meltctl a t of McKay and Milks.za The m.p. of 60-63" was raised t o 153-155 O . (i4-66" by one crystallization from methanol. Anal. Calcd. for CllHIfiN608: C, 36.0; H , 4.5; N, 33.3. A n a l . Calcd. for C ~ H S S F OC, ~ : 19.0; H , 3.2; N, 33.3. Found: C, 36.4; H, 4.4; N, 23.0. Found: C, 18.8; H, 3.0; S,33.2. 1-(a-Nitroxy-P-butyl)-j-nitroguanidine .-1-(a-Nitroxy1-( a-Hydroxybutyl )-3-guanidinium Sulfate .--Four grams p-butyl)-.'3-nitroguanidinc was obtained under conditions (0.05 mole) of 4-amino-1-butanol (prepared by the procedescribed for the preparation of l-(w-nitroxppropyl)-3-nidure of Tietzeg) was added to 5.6 g. (0.02 mole) of 2-methyltroguanidine. A 90% yield of product melting a t 99-100" 2-thiopseudouroniurn sulfate suspended in 10 cc. of water. was obtained. One crystallization from 95% ethanol raised The contents were allowed to stand at room temperature for the 111.p. to 100-109". three hours. The resultant clear solution was evaporated A n d . Calcd. for CjHIISj05: C, 27.1; H , 5.0; S , 31.7. almost t o dryness; 100 cc. of absolute cthanol was then added. The crystalline product which separated was re- Found: C, 27.2; H,4.8; S , 31.7. Attempts t o cyclize l-(a-nitroxy-~-but~~l)-3-nitroguanimoved by filtration and washed with 20 cc. of absolute ethanol. A 46.3910 yield (3.3 g.) of l-(w-hydroxybutyl)-3- dine to l-nitro-2-am~no-4-ethyl-A~-l,3-diazacyclopenteneguanidiniuin sulfate melting at 161-166" was obtained. nitrate salt were unsuccessful. T h e compound was reTwo crystallizations from 957, cthanol raiscd the m.p. to fluxed in n-butanol for periods ranging from one t o five hours without change. 168-169". 1-(p-Hydroxy-t-butyl)-3-guanidinium Sulfate.-2-AminoAnal. Calcd. for C10H?8K~O6S: C , 33.3; H, 7.8; K, 2-methyl-1-propanol (Eastman Kodak; 8.9 g., 0.1 mole) 23.4. Found: C,33.5; H , 7 . 8 ; N,23.5. was mixed together with 13.9 g. (0.05 mole) of 2-methyl-2l-(w-Hydroxybutyl)-3-guanidinium nitrate mas obtained thiopseudouronium sulfate and 20 cc. of water. The conin a n analogous manner described for the preparation of 1- tents wa$ allowed to stand at room temperature for ten days. (w-h~-droxypropyl)-3-guanidinium nitrate. A 927' yield The clear solution was then evaporated almost to dryness: of product melting a t 1l5-11Go was obtained. One crystalli- 200 cc. of absolute ethanol was added causing the immediate zation from 957, ethanol raised the m.p. t o 116-117'. precipitation of a white crystalline compound (m.p. 182183'). One crystallization from 95% ethanol raised the ( i ) (a) .I.P. N. Franchimont ancl E . 4.Klobbie, Rec I r n u chim., 7, m.p. to 185187'. The compound contained one molecule 349 (1888); (b) A , F h1cKa.y and D . F.IIanchester, Tins JUURKAL. of water of crystallization. 71, 1873 (1948). Anal. Calcd. for C I O H ~ O ~ ' ~ OC,; S 31.7; : H, 7.9; N, (8) A . F.ArcKay and G. I7 JTright, ibid.,7 0 , 3900 (1'748). 22.2. Found: C, 31.8; H , 7.7; iLT,22.5. (9) E Tietze, German Patent 730,337 (10.13). O.
June 20, 1954
NOTES
3219
We now wish to report that when the amination reaction was extended to include organosilicon Anal. Calcd. for ClIH16?\T608: C , 36.6; H, 4.5; N, compounds, trimethyl-(p-bromophenyl)-silanewas 23.3. Found: C, 36.2; H , 4 . 3 ; N, 23.1. observed t o react with lithium dimethylamide in l-(p-Nitroxy-t-butyl)-3-nitroguanidine.-l-(P-Nitroxy-tbutyl)-3-nitroguanidine was prepared in 91% yield (m.p. ether and in a benzene-ether mixture to form the expected trimethyl-(m-dimethylaminopheny1)-sil113-115') by the method described for the preparation of l-(w-nitroxypropyl)-3-nitroguanidine. One crystallization ane and some trimethyl-(p-dimethylaminopheny1)from 95% ethanol yielded crystals Yelting a t 112-114", silane. resolidifying and remelting a t 175-177 . The picrate salt, crystallized from ethanol, melted a t
195-196'.
Anal. Calcd. for C ~ H I I N ~ OC, S :27.1; H , 5.0; N, 31.7. Found: (2,273; H , 5.0; N, 32.1. l-Nitro-2-amino-4-dimethyl-Az-l ,3-diazacyclopentene Nitrate.-l-(~-Nitroxy-t-butyl)-3-nitroguanidine(0.3 g., 0.001 mole) was refluxed with 6 cc. of n-butanol for one-half hour. The solution was evaporated to 1 cc. and 10 cc. of absolute ethanol then added; the cyclic product, 0.2 g., separated out. The m.p. of 175-177' was raised to 179181' by one crystallization from absolute ethanol. Anal. Calcd. for C Z H I I S ~ O ~ C :, 27.1; H, 5.0; Ti, 31.7. Found: C,27.3; H, 5.2; X,32.0. 1-(~-Hydroxyamyl)-3-guanidiniumNitrate .-1-( wHVtiroryamyl)-3-guanidinium nitrate was prepared in 50'% yield (m.p. 108-110') bp the procedure described for the preparation of 1-(w-hydrouyprop -1)-3-guanidinium nitrate. One crystallization from QjyOethanol raised the m.p. to llO-lllo.
. I n n l . Cdlcd. for CtiH1tiS104: C, 34.7; H , 7.7; N,27.0Found: C, 34.7; H , 8.0; N, 26.6. 1-(~-Nitroxyamyl)-3-nitroguanidine .--1-( w-Nitrouyarn!-l)-3-riitroguanidinewas prepared in 94.3yo yield (m,.p. 102-103') bl- the procedure described for the preparation of 1-(w-nitroxypropyl)-3-nitroguanidine. One crystallization from ethanol raised the m.p. to 103-104". Anal. Calcd. for C6H13N506: C, 30.7; H , 5.5; N, 29.8. Found: C,30.7; H , 5.7; N,30.3. Attempts t o cyclize 1-(w-nitroxyamyl)-3-nitroguanidinet o l-nitro-2-amino-Az-l,3-diazacyclooctene by analogous conditions described for the cyclization of 1-(w-nitroxypropy1)3-nitroguanidine were unsuccessful. .4 mixed m .p. of the recovered product with an authentic sample was not depressed.
+
(CH3)3SiC6H4Br-p LiS(CH3)z --+ (CH3)SSiC6H4N(CH3)~-ih LiBr ( CH3)3SiC~H4N( CH3)2-m
+
In the initial experiments, the only product believed isolated was the unrearranged or para isomer. Identification of the structure of the amination product was made by comparing its picrate with that of authentic trimethyl-(p-dimethylaminophenyl) -silane3 which was prepared from trimethylchlorosilane and p-dirnethylaminophenyllithiuni. (CH3),SiC1
+ (CH,)2XCsH4Li-i)--+
+
( CH~:aSiCti€14S(CH3)2-P LiCl
Since there exists reasonable doubt as to the reliability of identification by the mixed melting points of picrates,* further work was carried out. The subsequent experiments showed that the rearranged or meta isomer was the predominant product. The structure of this material was confirmed by comparing its infrared spectrum with that of the product obtained from the reaction of nz-dimethylaminophenyllithium and trimethylchlorosilane.
+ (CH3)&TsHaLi-m
( CH3)3SiC1
+
+
(CH3)3SiC6H4N(CH3)~-m LiCl
These results are in general agreement with the one noted earlier in which the reaction of triphenyl(p-bromophenyl)-silane with lithium dimethylamide under corresponding conditions yielded largely RESEARCH A X D DEVELOPMENT DEPARTMEXT U. S. NAVALPOWDER FACTORY triphenyl-(m-dimethylaminophenyl)-silane.s In INDIAN HEAD,MARYLAND each instance, some unreacted starting material was recovered. Furthermore, it is probable that the unresolved reaction mixture may have contained The Reaction of Trimethyl-(p-bromopheny1)-silane other products formed in what appears to be a comwith Lithium Dimethylamide plex reaction. BY HENRYGILMAN, H. 1%'. MELVIXA N D JACK J. GOODMAN SEPTEMBER 28, 1953 RECEIVED
The reaction of certain 0- and p-halophenyl compounds with metal amides in liquid ammonia and with lithium dialkylamides in ether has been found to result in the formation of m-amino derivatives. For example, o-halophenyl methyl sulfides and obromophenyl methyl sulfone react with metal amides in liquid ammonia to yield the respective mamino compounds,' and m-dialkylaminoanisoles are formed when 0- and p-haloanisoles are treated with lithium dialkylarnides in ether.Ya Similarly, o-chlorotrifluoromethylbenzene reacts with sodium amide in liquid ammonia to give m-aminotrifluoromethylbenzene. ?b (1) H . Gilman a n d G . A. Martin, THISJOURNAL. 7 4 , 5317 (1952). (2) (a) See H. Gilman and R. H. Kyle, ibid., 7 4 , 3027 (1952), for general references t o rearrangement aminations b y alkali amides in liquid ammonia, and b y lithium dialkylamides in ether; (b) R. A. Benkeser and R. G. Severson, ibid.,71,3838 (1949); (c) H. Gilman and S Avakian, ibid., 6'7, 349 (1945). For two very recent references see: K . A. Benkeser a n d G. Schroll, ibid.. 76,3196 (1953), and J. D. Roberts, TI. E. Simmons, J r . , L. A. Carlsmith and C. W. Vaughan, i b i d . , 76, 3290 (1953).
Experimental
Trimethyl-(p-bromopheny1)-silane.-In a typical prcparation of this compound, 47.2 g. (0.20 mole) of p-dibromobenzene was dissolved in sufficient ether t o ensure complete solution at -15' in a reaction flask submerged in a Dry Ice-acetone-bath. T o this solution was added 0.194 mole of n-butyllithium6 a t the rate of 5 ml. per minute. Color Test 11-A' became negative after 20 minutes. Then, 19.5 g. (0.18 mole) of trimethylchlorosilane in ether was added a t such a rate t h a t the temperature of the reaction mixture did not rise above -IOo.* After all the trimethylchloro(3) H. Gilman and F. J . Marshall. ibid.,71, 2066 (1940). (4) I,. Ruzicka and L. Ehmann, H e l v . C h i m . Acln, 16, 140 (1032). ( 5 ) H. Gilman and H. W. Melvin, THISJ O U R N A L , 72, 995 (1950). ( 6 ) ?t-Butyllithium was prepared by t h e directions of H. Gilman, J. A . Beel, C. G. Brannen, M . W. Bullock, G. E. Dunu and L. S. Miller, i b i d . , 71, 1499 (1949). T h e titer was determined by the double titration method of H. Gilman and A . H. Haubein, i b i d . , 66, 1515 (1944). (7) H . Gilman a n d J. Swiss, ibid., 62, 1817 (1940). (8) In t h e preparation of trimethyl-(p-bromophenyl)-silane,it was found t h a t better yields are obtained if t h e halogen-metal interconversion reaction a n d t h e subsequent addition of trimethylchlorosilane are carried out a t -15 t o -10'. I f these precautions are not observed, lower yields of t h e desired product result, a n d a high-boiling fraction also forms. See H. Gilman, W. Langham and F. W. Moore, i b i d . , 62, 2327 (1040). for the effectsof temperature on side reactions in halogen-metal interconversion reactions.
